Sized pulp stock and product therefrom



Patented July 18, 1933 UNITED STATES PATENT OFFICE WALTER H. RANDALL, OI! WATERVILLE, MAINE, ASSIGNOR, BY MESNE ASSIGNMENTS, TO FIDELITY TRUST COMPANY, OF PORTLAND, MAINE, A CORPORATION OF MAINE,

TRUSTEE SIZED PULP STOCK'AND.PRODUCT THEREFROM No Drawing.

- My present invention relates to the production of articles from pulp stock and particularly to the art of moulding containers and like articles formed on a die from such stock as ground wood pulp,.ground wood and chemical fibre ulp, any fibrous pulp material, or any of these materials in combination.

It is frequently desired to have such pulp stock suitably sized and the articles either waterproof or greaseproof, or both, and for these as well as other purposes it has been customary to introduce sizing into pulp stock including chemical treatments productive of emulsification or saponification. These while in part successful have been more or less uncertain and at times resultantly inconsistent in practice and have by their very nature introduced materials and conditionsnot necessary and generally undesirable in that they produced complications in the manufacturing process.

My present invention contemplates results as to pulp or pulp made articles providing a complete sizing with rosin, wax, paraflin, or

other similar well known ingredients, used acterized by the presence of unmodified Application filed June 24, 1929. Serial No. 373,486.

rosin, wax, parafiin, or like sizing material distributed throughout the main body of the pulp in a state of mechanical mixture. It'

solution which may then be handled in any i usual way and from which articles may be formed as by suction on perforated or screened dies without danger of plugging of the dies by reason of the gathering of the s1z1ng.

Such a product,'furthermore, not having any extraneous reactants is not subject to any of the uncertainties of chemical change or decomposition such as have been common in the past. The articles produced from such pulp when dried out by heat as is usual in practice, show high qualities of grease and water-proofness and are of high structural quality and texture and are capable of excellent finish.

As illustrative of the manner of production of such a stock I will describe characteristic ingredients and steps which contribute to such manufactures generally and especially to the manufacture of grease and waterproof containers.

I cite for example paraffin as a characteristic wax, which may be in pure or in blended state as desired and'may be'and preferably is in unemulsified and unsaponified form and 7 therefore need have no unstable or reactive characteristics, although obviously I may use any of, the other well known sizing materials, as rosin, wax, or the like, either singly or in combination.

As a carrier for such a size I employ fibre and preferably a wood fibre. For certain reasons which I will hereafter explain, I prefer that this fibre be a chemical fibre as distinguished from an untreated wood fibre,

'such as the ground pulp usually used, al-

' by weight of size to the fibre.

though I may use any other fibres possessing equivalent qualities.

Such fibre and the sizing material, such as rosin, wax, or the like, is worked together, preferably in the proportion of about 25% The original mixture should be effected with the fibre dry and the size hot. This may be accomplished by rolling or rubbing the size into or onto the fibre mass in a mixing operation, or by impregnation, to efl'ect a complete dispersion.

A complete dry mixture maybe made in this way, after which the mixture is preferably carried on to a water phase in which the product becomes a pulpy solution of such fluidity as to be capable of ready introduction into the pulp stream of the heaters or in the J ordan; This fibrously dispersed size is thereforea new type of sizing mixture having distinct advantages as specified.

Upon arrival at the machines, the pulp thus sized will be found in complete mixture andfree from coagulation or flocculation, so

that it can be picked up by suction on finely perforated or screened dies without tendency to clog.

The articles "from such machines, moreover, in drying develop under the usual drying temperatures (of say 250 to 400 no unfavorable peculiarities but on the contrary seem to have a more perfect fusion of the size and a more complete and uniform sizing. As the size has not been subjected to any chemical modification it undergoes its thermal changes in close approximation to its normal performance when in a free state.

Various fibres, vegetable or otherwise, may be used, but the wood fibres are of advantage on account of cheapness and because the ultimate fibre body is of like kind as where a chemical fibre is used with ground pulp.

In regard to my preference for chemicalfibre I have found an advantage in using such afibre and of having such fibre dry, but n a slightly hydrated state. Without wishing to be limited thereby I would suggest'that the slight hydration of such fibre apparently modifies the fibre surface and there is apparently a more complete attenuation of the size in its distribution onsuch fibre surface.

To get the best results I find that it is well to, have the wax or other sizing material lodged as far as possible within the fibre as distinguished from a mere external coating or surface impregnation. If therefore a fibre mixture of sizing is used in which there is a minimum of sizing on the surface of the fibre, there is less tendency of the fibre to bunch and the dispersion in the pulp or other body stock solution will be more complete, giving a more uniform and more completely sized article. In this, the fibres themselves act as protective coatings for the en-.

' trapped size with which they are impregnat The mixture of size and fibre may, however, be a mechanical mixture wherein the size is on the fibre only as a surface coating, or where hydrated fibre as distinguished from plain fibre is used, the mixture may be either a surface coating or a partial impregnation. or both, and my invention is to be understood as including several conditions, all of which have been observed by me in my work.

As before stated, my product may be produced in various ways, those described being simple and therefore of practical value as to efliciency and economy. My novel pulp and novel sizing ingredient may be used for various purposes, but as pointed out they have a conspicuous utility for use with moulding machines having perforate or foraminous dies. The products produced may also be for any purpose and while their sizing has been particularly discussed in relation to grease-proofness and water-proofness, this has been done merely because of the great deside for such articles and not in any intention to specify these characteristics as limitations.

What I therefore claim and desire to secure by Letters Patent is 1. A sizing mixture for a pulp solution,

. comprising a fibrous medium having a subcomprising a fibrous medium having on its surface a deposit of unmodified size.

4. A sizing mixture for a pulp solution, comprising a mechanical mixture of unmodified size and fibres.

5. A sizing mixture for a pulp solution, comprising a mechanical mixture of unmodified size and hydrated fibres.

6. A pulp solution for die moulding, comprising a liquid pulp solution, and a' mixture of fibres and unmodified size. I

7 A pulp solution for die moulding, comprising a liquid pulp solution, and a mixture of fibres and unmodified size, the fibres being penetrated by the size.-

8. A pulp solution for die moulding, comprising a liquid pulp solution, and a mixture of fibres and unmodified size, the size being present on the fibres as a surface coating.

9. As a new article of manufacture, a container moulded from a pulp solution and having a chemically unmodified size therein consisting of a mechanical mixture of fibres and size.

10. As a new article of manufacture, a

.moulded container having a chemically un- 11. As a new article of manufacture, a moulded container having a greaseproofing agent consisting of a mixture of fibres and chemically unmodified size.

12. As a new article of manufacture, a grease and Waterproof container moulded from a liquid pulp solution and having a greaseproofing agent consisting of a mixture of fibres and chemically unmodified size distributed throughout the liquid pulp solution.

13. As a new article of manufacture, a grease and Waterproof container moulded from a liquid pulp solution and having a greaseproofing agent consisting ofa mixture of hydrated fibres and unmodified size dising of a mechanical mixture of substantially unmodified size and fibres.

17. A sizing mixture for pulp stock for mechanical fabrication comprising a mixture of fibres and an untreated size.

18. As a greaseproofer for fibrous articles, size and fibres dry mixed together to form a sizing mixture consisting of size carrying fibres which during the heating process are uniformly mixed with the unsized fibres of the beater furnish.

19. A sizing mixture consisting of an unheated mixture of fibres and a sizing ingredient.

20. A sizing mixture consisting of an unheated mixture of fibres and Wax.

21. A sizing mixture for an aqueous pulp solution, consisting of a' dry mixture of fibres and a sizing ingredient.

22. A sizing mixture for an aqueouspulp solution consisting of a dry mixture of fibres and Wax.

23. For incorporation in an unheated aqueous pulp solution, a dry mixture of fibres and a sizing ingredient.

WALTER H. RANDALL. 

